5BQ7: Crystal structure of chikungunya virus-human Fab 5F-10 fragment

UNLABELLED: Chikungunya virus is a positive-stranded RNA alphavirus. Structures of chikungunya virus-like particles in complex with strongly neutralizing antibody Fab fragments (8B10 and 5F10) were determined using cryo-electron microscopy and X-ray crystallography. By fitting the crystallographically determined structures of these Fab fragments into the cryo-electron density maps, we show that Fab fragments of antibody 8B10 extend radially from the viral surface and block receptor binding on the E2 glycoprotein. In contrast, Fab fragments of antibody 5F10 bind the tip of the E2 B domain and lie tangentially on the viral surface. Fab 5F10 fixes the B domain rigidly to the surface of the virus, blocking exposure of the fusion loop on glycoprotein E1 and therefore preventing the virus from becoming fusogenic. Although Fab 5F10 can neutralize the wild-type virus, it can also bind to a mutant virus without inhibiting fusion or attachment. Although the mutant virus is no longer able to propagate by extracellular budding, it can, however, enter the next cell by traveling through junctional complexes without being intercepted by a neutralizing antibody to the wild-type virus, thus clarifying how cell-to-cell transmission can occur. IMPORTANCE: Alphaviral infections are transmitted mainly by mosquitoes. Chikungunya virus (CHIKV), which belongs to the Alphavirus genus, has a wide distribution in the Old World that has expanded in recent years into the Americas. There are currently no vaccines or drugs against alphaviral infections. Therefore, a better understanding of CHIKV and its associated neutralizing antibodies will aid in the development of effective treatments.
PDB ID: 5BQ7Download
MMDB ID: 134278
PDB Deposition Date: 2015/5/28
Updated in MMDB: 2015/11
Experimental Method:
x-ray diffraction
Resolution: 2.738  Å
Source Organism:
Similar Structures:
Biological Unit for 5BQ7: dimeric; determined by author and by software (PISA)
Molecular Components in 5BQ7
Label Count Molecule
Proteins (2 molecules)
FAB 5f-10-heavy Chain
Molecule annotation
FAB 5f-10-light Chain
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB